The human spine is a biomechanical structure with thirty-three vertebral members, and is responsible for protecting the spinal cord, nerve roots and internal organs of the thorax and abdomen. The spine also provides structural support for the body while permitting flexibility of motion. A significant portion of the population will experience back pain at some point in their lives resulting from a spinal condition. The pain may range from general discomfort to disabling pain that immobilizes the individual. Back pain may result from a trauma to the spine, the natural aging process, or the result of a degenerative disease or condition.
Procedures to address back problems sometimes require correcting the distance between spinous processes by inserting a device (e.g., a spacer) therebetween. The spacer, which is carefully positioned and aligned within the area occupied by the interspinous ligament, after removal thereof, is sized to position the spinous processes in a manner to return proper spacing thereof.
Dynamic interspinous spacers are currently used to treat patients with a variety of indications. Essentially, these patients present a need for distraction of the posterior elements (e.g., the spinal processes) using a mechanical device. Current clinical indications for the device, as described at SAS (Spine Arthroplasty Society) Summit 2005 by Guizzardi et al., include stenosis, disc herniation, facet arthropathy, degenerative disc disease and adjacent segment degeneration.
Marketed interspinous devices include rigid and flexible spacers made from PEEK, titanium or silicone. Clinical success with these devices has been extremely positive so far as an early stage treatment option, avoiding or delaying the need for lumbar spinal fusion. However, all devices require an open technique to be implanted, and many require destroying important anatomical stabilizers, such as the supraspinous ligament.
Current devices for spacing adjacent interspinous processes are preformed, and are not customizable for different sizes and dimensions of the anatomy of an interspinous area of an actual patient. Instead, preformed devices of an approximately correct size are inserted into the interspinous area of the patient. Further, the stiffness or flexibility of the devices must be determined prior to the devices being inserted into the interspinous area.
Thus, a need exists for improvements to surgical spacers, such as those for spacing adjacent interspinous processes.